DACA, SIJS & U-Visas

After the Dream Act died in Congress, President Obama announced a policy of enforcement discretion, Deferred Action for Childhood Arrivals (DACA) which targeted the same group of young people. If they qualified, DACA provided two years of discretion from deportation and a work permit. In November 2014, President Obama announced a plan to apply the same discretion to parents of US citizen children. What does this enforcement discretion look like? How much can the President do without action by Congress?